Organic Light Emitting Display Device and Method of Manufacturing the Same

ABSTRACT

Disclosed are an organic light emitting display device and a method of manufacturing the same. In the organic light emitting display, an anode connected to a thin film transistor and a bank disposed along the edge of the anode are simultaneously formed through one mask process, and a partition is formed to cover the side surface of the anode, thereby preventing damage to a pad cover electrode by an etching solution or etching gas of the anode without any separate pad protective film.

CROSS-REFERENCE TO RELATED APPPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/799,763 filed on Oct. 31, 2017, which claims priority toRepublic of Korea Patent Application No. 10-2016-0143900, filed on Oct.31, 2016, all of which are incorporated by reference herein.

BACKGROUND Field of Technology

The present disclosure relates to an organic light emitting displaydevice and a method of manufacturing the same, and more particularly, toan organic light emitting display device with simplified structure andmanufacturing process and a method of manufacturing the same.

Discussion of the Related Art

Display devices, which display various pieces of information on ascreen, are a core technology in the age of information andcommunication and have been developed to satisfy thinness, light-weight,portability and high-performance trends. As representative displaydevices, a liquid crystal display (LCD), an organic light emitting diode(OLED) display, etc. are used now.

In order to manufacture a display device, a mask process using aphotomask is performed several times. In each mask process,sub-processes, such as cleaning, exposure to light, development,etching, etc., are carried out. Therefore, whenever one mask process isadded, manufacturing time and manufacturing costs of the display deviceare raised and defect rate is increased, lowering the manufacturingyield. Therefore, an organic light emitting display device withsimplified structure and manufacturing process to reduce manufacturingcosts and to enhance manufacturing yield and production efficiency hasbeen required.

SUMMARY

Accordingly, the present disclosure is directed to an organic lightemitting display device and a method of manufacturing the same thatsubstantially obviate one or more problems due to limitations anddisadvantages of the related art.

An object of the present disclosure is to provide an organic lightemitting display device with simplified structure and manufacturingprocess and a method of manufacturing the same.

Additional advantages, objects, and features of the disclosure will beset forth in the description which follows and will become apparent tothose having ordinary skill in the art upon examination of the followingor may be learned from practice of the disclosure. The objectives andother advantages of the disclosure may be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the disclosure, as embodied and broadly described herein, anorganic light emitting display device includes thin film transistorsdisposed on a substrate, organic light emitting elements connected tothe thin film transistors, a bank disposed along the edge an anode ofeach of the organic light emitting elements, and a partition disposed tocover the side surface of the anode.

In another aspect of the present disclosure, a method of manufacturingan organic light emitting display device includes forming thin filmtransistors disposed on a substrate, forming an anode connected to eachof the thin film transistors and forming a bank disposed along the edgean anode, simultaneously, and forming a partition disposed to cover theside surface of the anode.

It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure areexemplary and explanatory and are intended to provide furtherexplanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the disclosure andtogether with the description serve to explain the principle of thedisclosure. In the drawings:

FIGS. 1A to 1D are cross-sectional views illustrating a method ofmanufacturing a conventional organic light emitting display device;

FIG. 2 is a plan view of an organic light emitting display device inaccordance with one embodiment of the present disclosure;

FIG. 3 is a cross-sectional view illustrating the organic light emittingdisplay device shown in FIG. 2;

FIG. 4 is a cross-sectional view of an organic light emitting displaydevice in accordance with another embodiment of the present disclosure;

FIGS. 5A to 5I are cross-sectional views illustrating a method ofmanufacturing the organic light emitting display device shown in FIG. 3;and

FIGS. 6A to 6D are cross-sectional views illustrating a method ofmanufacturing an anode, an auxiliary connection electrode, a pad coverelectrode and a bank shown in FIG. 5H.

DETAILED DESCRIPTION

Prior to description of the embodiments of the present disclosure,productivity decrease due to a mask process of a conventional organiclight emitting display device will be exemplarily described below.

FIGS. 1A to 1D are cross-sectional views illustrating a method ofmanufacturing a conventional organic light emitting display device.

As exemplarily shown in FIG. 1A, a pixel cover electrode 14 disposed tocover a pixel connection electrode 12 contacting a drain electrode 10and a pad cover electrode 54 disposed to cover a pad connectionelectrode 52 contacting a pad electrode 50 are formed on a substrate 1.Here, the pad connection electrode 52 is conductively connected to thepad electrode 50 exposed by a first insulating layer 22, and the pixelconnection electrode 12 conductively connected to the drain electrode 10exposed by the first and second insulating layers 22 and 24. And, thepixel cover electrode 14 and the pad cover electrode 54 are formed of atransparent conductive film having high corrosion resistance and highacid resistance.

Thereafter, as exemplarily shown in FIG. 1B, a planarization layer 26having a pixel contact hole 28 to expose the pixel cover electrode 14 isformed, and the pad protective film 56 to cover the pad cover electrode54 is formed. Here, the pad protective film 56 is formed of a materialwhich is removable by a strip solution subsequently used in a process ofstripping a photoresist pattern used in formation of an anode 32.

Thereafter, as exemplarily shown in FIG. 1C, the anode 32 connected tothe pixel cover electrode 14 through the pixel contact hole 28 isformed. Here, if the anode 32 is applied to a front view type organiclight emitting display device, the anode 32 has a structure in which atransparent conductive film and an opaque conductive film are stacked.

When the anode 32 is formed, the pad protective film 56 covers the padcover electrode 54 and thus prevents the pad cover electrode 54 frombeing damaged by an etching solution used in formation of the anode 32.

Thereafter, as exemplarily shown in FIG. 1D, a photoresist pattern 58remaining on the anode 32 and the pad protective film 56 remaining onthe pad cover electrode 54 are removed through the stripping process.

As such, in the conventional organic light emitting display device, theanode 32 includes the opaque conductive film which may be corrosive and,thus, it is difficult to simultaneously form the anode 32 and the padcover electrode 54. Further, in the conventional organic light emittingdisplay device, in order to prevent the pad cover electrode from beingdamaged by the etching solution used in formation of the anode 32, thepad protective film 56 to cover the pad cover electrode 54 should beseparately formed.

Therefore, in the conventional organic light emitting display device, inorder to form the pad cover electrode 54 and the pad protective film 56,the number of times that the mask process is performed is increased byat least two times and thus productivity is lowered and manufacturingcosts are raised.

In order to solve these problems of the method of manufacturing theconventional organic light emitting display device, in a method ofmanufacturing an organic light emitting display device in accordancewith the present disclosure, formation of a bank, an anode and a padcover electrode and exposure of the pad cover electrode aresimultaneously executed through one mask process and the number of timesthat the mask process is performed is decreased by at least three timesand, thus, productivity is improved and manufacturing costs are reduced.

Reference will now be made in detail to the preferred embodiments of thepresent disclosure, examples of which are illustrated in theaccompanying drawings.

FIG. 2 is a plan view of an organic light emitting display device inaccordance with one embodiment of the present disclosure, and FIG. 3 isa cross-sectional view illustrating the organic light emitting displaydevice shown in FIG. 2.

The organic light emitting display device shown in FIGS. 2 and 3 isprovided with an active area and a pad area.

In the pad area, a plurality of pads 150 to respectively supply drivingsignals to scan lines SL, data lines DL, a high voltage (VDD) supplyline 161 and a low voltage (VSS) supply line 160 is formed.

Each of the pads 150 includes a first pad electrode 152, a second padelectrode 154 and a pad cover electrode 156.

The first pad electrode 152 is formed of the same material as a gateelectrode 106 on a gate insulating pattern 112 having the same shape asthe first pad electrode 152.

The second pad electrode 154 is conductively connected to the first padelectrode 152 exposed through a first pad contact hole 158 a formedthrough an interlayer insulating film 116. The second pad electrode 154is formed of the same material as source and drain electrodes 108 and110 on the interlayer insulating film 116 formed in the same layer asthe source and drain electrodes 108 and 110.

The pad cover electrode 156 is conductively connected to the second padelectrode 154 exposed through a second pad contact hole 158 b formedthrough a protective film 118. The pad cover electrode 156 is formed ofthe same material as a lower conductive film 131 a included in an anode132.

In the active area, a plurality of sub-pixels is arranged in a matrixand thus an image is displayed. Each of the sub-pixels arranged in theactive area includes a pixel driving circuit disposed in a circuit areaCA and a light emitting element 130 connected to the pixel drivingcircuit.

The pixel driving circuit includes a switching transistor T1, a drivingtransistor T2 and a storage capacitor Cst.

The switching transistor T1 is turned on when a scan pulse is suppliedto the scan line SL, and supplies a data signal supplied to the dataline DL to the storage capacitor Cst and a gate electrode of the drivingtransistor T2.

The driving transistor T2 controls current I supplied from the highvoltage supply line 161 to the light emitting element 130 in response tothe data signal supplied to the gate electrode of the driving transistorT2, thus adjusting an amount of light emitted from the light emittingelement 130. Further, even if the switching transistor T1 is turned off,the driving transistor T2 supplies constant current I due to voltagecharging the storage capacitor Cst until a data signal of a next frameis supplied, and thus maintains emission of light from the lightemitting element 130.

For this purpose, the driving transistor T2, as exemplarily shown inFIG. 3, includes the gate electrode 106, the source electrode 108, thedrain electrode 110 and an active layer 114.

The gate electrode 106 is formed on the gate insulating pattern 112having the same shape as the gate electrode 106. The gate electrode 106overlaps a channel area of the active layer 114 under the condition thatthe gate insulating pattern 112 is interposed there between. The gateelectrode 106 may have a single layer structure including one selectedfrom the group consisting of molybdenum (Mo), aluminum (Al), chrome(Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper(Cu) or an alloy thereof or have a multilayer structure including thesame, but the present disclosure is not limited thereto.

The source electrode 108 is connected to a source region of the activelayer 114 through a source contact hole 124S formed through theinterlayer insulating film 116. The drain electrode 110 is connected toa drain region of the active layer 114 through a drain contact hole 124Dformed through the interlayer insulating film 116. Further, the drainelectrode 110 is exposed through a first pixel contact hole 120 formedthrough the protective film 118 and is thus connected to a pixelconnection electrode 148.

The source electrode 108 and the drain electrode 110 may have, forexample, a single layer structure including one selected from the groupconsisting of molybdenum (Mo), aluminum (Al), chrome (Cr), gold (Au),titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu) or an alloythereof or have a multilayer structure including the same, but thepresent disclosure is not limited thereto.

The active layer 114 is provided with the source region and the drainregion which are opposite each other across a channel region interposedtherebetween. The channel region overlaps the gate electrode 106 underthe condition that the gate insulating pattern 112 is interposedtherebetween. The source region is connected to the source electrode 108through the source contact hole 124S, and the drain region is connectedto the drain electrode 110 through the drain contact hole 124D. Each ofthe source region and the drain region is formed of a semiconductormaterial doped with an n-type or p-type impurity, and the channel regionis formed of a semiconductor material doped with no n-type or p-typeimpurity.

A buffer film 104 and a light shielding layer (not shown) are formedbetween the active layer 114 and the substrate 101. The light shieldinglayer is formed on the substrate 101 to overlap the channel region ofthe active layer 114. Such a light shielding layer absorbs or reflectslight incident from the outside and may thus minimize light incidentupon the channel region. Here, the light shielding layer may be exposedthrough a buffer contact hole (not shown) formed through the buffer film104 and be conductively connected to the active layer 114. The lightshielding layer is formed of an opaque metal, such as Mo, Ti, Al, Cu,Cr, Co, W, Ta or Ni.

The buffer film 104 has a single layer structure or a multilayerstructure formed of silicon oxide or silicon nitride on the substrate101 formed of glass or plastic resin, such as polyimide (PI). The bufferfilm 104 prevents diffusion of moisture or impurities generated from thesubstrate 101, or adjusts a transfer speed of heat in crystallization,thus serving to facilitate crystallization of the active layer 114.

The storage capacitor Cst is formed by overlapping a storage lowerelectrode 142 and a storage upper electrode 144 each other whileinterposing the interlayer insulating film 116 therebetween. Here, thestorage lower electrode 142 is formed of the same material as the gateelectrode 106 in the same layer as the gate electrode 106, and thestorage upper electrode 144 is formed of the same material as the sourceelectrode 108 in the same layer as the source electrode 108. Even if theswitching transistor T1 is turned off, the driving transistor T2supplies constant current I due to voltage charging the storagecapacitor Cst until a data signal of a next frame is supplied, and thusmaintains emission of light from the light emitting element 130.

The light emitting element 130 includes the anode 132 connected to thedrain electrode 110 of the driving transistor T2, at least one organiclight emitting stack 134 formed on the anode 132, and a cathode 136formed on the organic light emitting stack 134.

The anode 132 is disposed on the planarization layer 126 to overlap anemission area EA prepared by a bank 138 and the circuit area CA providedwith the pixel driving circuit.

The anode 132 has a structure in which a lower conductive film 131 a andan upper conductive film 131 b are sequentially stacked, in the samemanner as an auxiliary connection electrode 168. Here, the side surfacesof the bank 138 and the lower conductive film 131 a of each of the anode132 and the auxiliary connection electrode 168 protrude more than theside surface of the upper conductive film 131 b of each of the anode 132and the auxiliary connection electrode 168. The lower conductive film131 a is formed of a material which is not corroded by oxygen andmoisture, even if the lower conductive film 131 a is exposed to theoutside, and is not damaged during etching of the upper conductive film131 b. For example, the lower conductive film 131 a may be formed of oneselected from the group consisting of molybdenum-titanium (MoTi),titanium (Ti), tantalum (Ta) and combinations thereof. The upperconductive film 131 b has a multilayer structure including a transparentconductive film and an opaque conductive film having high reflectionefficiency. The transparent conductive film is formed of a materialhaving a comparatively high work function value, such asindium-tin-oxide (ITO) or indium-zinc-oxide (IZO), and the opaqueconductive film is formed to have a single layer structure or amultilayer structure including Al, Ag, Cu, Pb, Mo, Ti or an alloythereof. For example, the upper conductive film 131 b may be formed tohave a structure in which a transparent conductive film, an opaqueconductive film and a transparent conductive film are sequentiallystacked, or a structure in which a transparent conductive film and anopaque conductive film are sequentially stacked.

The anode 132 is conductively connected to the drain electrode 110through the pixel connection electrode 148. Here, the pixel connectionelectrode 148 contacts the drain electrode 110 through the first pixelcontact hole 120 formed through the protective film 118. Further, thepixel connection electrode 148 contacts the anode 132 through a secondpixel contact hole 128 formed through the planarization layer 126. Onthe other hand, the anode 132 may contact the drain electrode 110through a pixel contact hole formed through the protective film 118 andthe planarization layer 128 without a separate pixel connectionelectrode 148.

The organic light emitting stack 134 is formed by stacking a holerelating layer, an organic light emitting layer and an electron relatinglayer on the anode 132 in regular order or in reverse order. Forexample, the organic light emitting stack 134 may include first andsecond light emitting stacks disposed opposite each other under thecondition that a charge generation layer is interposed therebetween. Inthis case, an organic light emitting layer of one of the first andsecond light emitting stacks generates blue light, and an organic lightemitting layer of the other of the first and second light emittingstacks generates yellowish green light, thus producing white lightthrough the first and second light emitting stacks.

If the organic light emitting stack 134 is applied to a front view typeorganic light emitting display device, the organic light emitting stack134 is formed on the anode 132 disposed not only in the emission area EAprepared by the bank 138 but also in the circuit area CA, and thus anaperture ratio is improved.

The bank 138 is formed on the anode 132 to prepare the emission area EA.The bank 138 may be formed of an opaque material (for example, a blackmaterial) to prevent optical interference between neighboringsub-pixels. In this case, the bank 138 may be formed of alight-shielding material including at least one of a color pigment, anorganic black pigment and carbon.

The organic light emitting stack 134 is separated from another organiclight emitting stack 134 disposed in a neighboring sub-pixel generatinglight of a different color from the color of light emitted from theformer organic light emitting stack 134 through a partition 146. Thatis, the partition 146 has a reverse tapered shape, the width of which isgradually increased from the lower surface thereof to the upper surfacethereof, and is disposed in a bank hole 174 overlapping the auxiliaryconnection electrode 168. Therefore, the organic light emitting stack134 grown to have straightness is not formed on the auxiliary connectionelectrode 168 overlapping the partition 146 and, thus, the organic lightemitting stacks 134 of the neighboring sub-pixels emitting light ofdifferent colors are separated from each other within the bank hole 174by the partition 146. In this case, the organic light emitting stack 134is formed in a remaining region except for the auxiliary connectionelectrode 168 exposed by the bank hole 174 and is thus formed only onthe upper surface of the anode 132 exposed by the bank 138, the uppersurface of the partition 146 and the upper and side surfaces of the bank138. On the other hand, the cathode 136 having better step coverage thanthe organic light emitting stack 134 is formed on the upper and sidesurfaces of the partition 146 and the side surface of the bank 138disposed under the partition 146 and thus contact between the cathode136 and the auxiliary connection electrode 168 is facilitated.

The cathode 136 is formed on the upper and side surfaces of the organiclight emitting stack 134 and the bank 138 to be opposite the anode 132under the condition that the organic light emitting stack 134 isinterposed therebetween. If the cathode 136 is applied to a front viewtype organic light emitting display device, the cathode 136 is formed ofa transparent conductive film, such as indium-tin-oxide (ITO) orindium-zinc-oxide (IZO).

The cathode 136 is connected to the low voltage supply line 160 in thebank hole 174, in which the partition 146 is located, through theauxiliary connection electrode 168. The auxiliary connection electrode168 is conductively connected to the low voltage supply line 160 exposedthrough an auxiliary contact hole 170 formed through the protective film118 and the planarization layer 128. Here, the low voltage supply line160 is formed of a data metal layer having higher conductivity than thecathode 136 and may thus compensate for high resistance of the cathode136 formed of a transparent conductive film, such as indium-tin-oxide(ITO) or indium-zinc-oxide (IZO).

The low voltage supply line 160 is formed of the same material as thestorage upper electrode 144 on the interlayer insulating film 116 whichis coplanar with the storage upper electrode 144. The low voltage supplyline 160 is exposed through the auxiliary contact hole 170 formedthrough the protective film 118 and the planarization layer 126 and isconnected to the auxiliary connection electrode 168.

The bank 138 of the present disclosureis formed along the edge of eachof the anode 132 and the auxiliary connection electrode 168, asexemplarily shown in FIG. 3. The bank 138 protrudes more than the sidesurface of each of the anode 132 and the auxiliary connection electrode168. In this case, an undercut is formed between the side surface ofeach of the anode 132 and the auxiliary connection electrode 168 and thebank 138. The partition 146 is formed to cover the side surfaces of theanode 132 and the auxiliary connection electrode 168 having an undercutstructure, as exemplarily shown in FIG. 3, thereby preventing electricalshort circuit between the side surface of the anode 32 and the cathode136. In this case, the cathode 136 contacts the upper surface of theauxiliary connection electrode 168 exposed by the bank 138.

Otherwise, the partition 146 may be formed to cover the side surface ofthe anode 132 having an undercut structure but may not be formed on theside surface of the auxiliary connection electrode 168 having anundercut structure. In this case, the side surface of the anode 132 isnot conductively connected to the cathode 136 by the partition 146 and,thus, electrical short circuit between the anode 132 and the cathode 136may be prevented. Further, since the side surface of the auxiliaryconnection electrode 168 having an undercut structure and the uppersurface of the auxiliary connection electrode 168 exposed by the bank138 are conductively connected to the cathode 136, a contact areabetween the auxiliary connection electrode 168 and the cathode 136 isincreased and thus high resistance of the cathode 136 may be lowered.

FIGS. 5A to 5I are cross-sectional views illustrating a method ofmanufacturing the organic light emitting display device shown in FIG. 3.

As exemplarily shown in FIG. 5A, a buffer film 104 is formed on asubstrate 101, and an active layer 114 is formed on the buffer film 104.

In more detail, the buffer film 104 is formed by depositing an inorganicinsulating material, such as SiO_(x) or SiN_(x), on the entire surfaceof the substrate 101. Thereafter, an amorphous silicon thin film isformed on the substrate 101 provided with the buffer film 104 through amethod, such as low pressure chemical vapor deposition (LPCVD) or plasmaenhanced chemical vapor deposition (PECVD). Thereafter, a polysiliconthin film is formed by crystallizing the amorphous silicon thin film.Thereafter, the polysilicon thin film is patterned through aphotolithography process and an etching process using a first mask, thusforming the active layer 114.

With reference to FIG. 5B, a gate insulating pattern 112 is formed onthe buffer film 104 provided with the active layer 114, and a gateelectrode 106, a storage lower electrode 142 and a first pad electrode152 are formed on the gate insulating pattern 112.

In more detail, a gate insulating film is formed on the buffer film 104provided with the active layer 114, and a gate metal layer is formedthereon through a deposition method, such as sputtering. An inorganicinsulating material, such as SiO_(x) or SiN_(x), is used as the gateinsulating film. The gate metal layer is formed to have a single layerstructure including a metal selected from the group consisting of Mo,Ti, Cu, AlNd, Al, Cr and an alloy thereof or to have a multilayerstructure including the same. Thereafter, the gate metal layer and thegate insulating film are simultaneously patterned through aphotolithography process and an etching process using a second mask,thereby forming the storage lower electrode 142, the gate electrode andthe first pad electrode 152 and forming the gate insulating pattern 112being the same shape as the storage lower electrode 142, the gateelectrode and the first pad electrode 152 thereunder.

Thereafter, an n⁺-type or p⁺-type impurity is injected into the activelayer 114 using the gate electrode 106 as a mask, thus forming sourceand drain regions of the active layer 114.

With reference to FIG. 5C, an interlayer insulating film 116 providedwith source and drain contact holes 124S and 124D and a first padcontact hole 158 a is formed on the substrate 101 provided with the gateelectrode 106, the storage lower electrode 142 and the first padelectrode 152.

In more detail, the interlayer insulating film 116 is formed on thesubstrate 101 provided with the gate electrode 106, the storage lowerelectrode 142 and the first pad electrode 152 through a depositionmethod, such as PECVD. Thereafter, the interlayer insulating film 116 ispatterned through a photolithography process and an etching processusing a third mask, thus forming the source and drain contact holes 124Sand 124D and the first pad contact hole 158 a. The source and draincontact holes 124S and 124D and the first pad contact hole 158 a areformed through the interlayer insulating film 116, thus exposing asource electrode 108, a drain electrode 110 and a first pad electrode152.

With reference to FIG. 5D, the source electrode 108, the drain electrode110, a storage upper electrode 144, a second pad electrode 154 and a lowvoltage supply line 160 are formed on the interlayer insulating film 116provided with the source and drain contact holes 124S and 124D and thefirst contact hole 158 a.

In more detail, a data metal layer is formed on the interlayerinsulating film 116 provided with the source and drain contact holes124S and 124D and the first contact hole 158 a through a depositionmethod, such as sputtering. The data metal layer is formed to have asingle layer structure including a metal selected from the groupconsisting of Mo, Ti, Cu, AlNd, Al, Cr and an alloy thereof or to have amultilayer structure including the same. Thereafter, the data metallayer is patterned through a photolithography process and an etchingprocess using a fourth mask, thus forming the source electrode 108, thedrain electrode 110, the storage upper electrode 144, the second padelectrode 154 and the low voltage supply line 160 on the interlayerinsulating film 116 on the interlayer insulating film 116.

With reference to FIG. 5E, a protective film 118 provided with a secondpad contact hole 158 b and a first pixel contact hole 120 is formed onthe interlayer insulating film 116 provided with the source electrode108, the drain electrode 110, the storage upper electrode 144, thesecond pad electrode 154 and the low voltage supply line 160.

In more detail, the protective film 118 is formed by depositing aninorganic insulating material, such as SiO_(x) or SiN_(x), on the entiresurface of the interlayer insulating film 116 provided with the sourceelectrode 108, the drain electrode 110, the storage upper electrode 144,the second pad electrode 154 and the low voltage supply line 160.Thereafter, the protective film 118 is selectively patterned through aphotolithography process and an etching process using a fifth mask, thusforming the second pad contact hole 158 b and the first pixel contacthole 120. The second pad contact hole 158 b and the first pixel contacthole 120 are formed through the protective film 118, thus exposing thedrain electrode 110 and the second pad electrode 154.

With reference to FIG. 5F, a pixel connection electrode 148 is formed onthe substrate 101 provided with the protective film 118 having thesecond contact hole 158 b and the first pixel contact hole 120.

In more detail, a connection metal layer is formed on the substrate 101provided with the protective film 118 having the second contact hole 158b and the first pixel contact hole 120 through a deposition method, suchas sputtering. Thereafter, the connection metal layer is patternedthrough a photolithography process and an etching process using a sixthmask, thus forming the pixel connection electrode 148.

With reference to FIG. 5G, a planarization layer 126 having a secondpixel contact hole 128 and an auxiliary contact hole 170 is formed onthe substrate 101 provided with the pixel connection electrode 148.

In more detail, the planarization layer 126 is formed by stacking aphotosensitive organic insulating material, such as photoacryl, on thesubstrate 101 provided with the pixel connection electrode 148.Thereafter, the planarization layer 126 is patterned through aphotolithography process using a seventh mask, thus forming the secondpixel contact hole 128 and the auxiliary contact hole 170.

With reference to FIG. 5H, an anode 132, an auxiliary connectionelectrode 168, a pad cover electrode 156 and a bank 138 are formed onthe substrate 101 provided with the planarization layer 126 having thesecond pixel contact hole 128 and the auxiliary contact hole 170 throughthe same mask process. This will be described below with reference toFIGS. 6A to 6D.

As exemplarily shown in FIG. 6A, a lower conductive film 131 a and anupper conductive film 131 b are sequentially formed on the substrate 101provided with the planarization layer 126 having the second pixelcontact hole 128 and the auxiliary contact hole 170. Here, the lowerconductive film 131 a is formed of a material which is not corroded byoxygen and moisture, even if the lower conductive film 131 a is exposedto the outside, and is not damaged during etching of the upperconductive film 131 b. For example, the lower conductive film 131 a maybe formed of one selected from the group consisting ofmolybdenum-titanium (MoTi), titanium (Ti), tantalum (Ta) andcombinations thereof. The upper conductive film 131 b has a multilayerstructure including a transparent conductive film and an opaqueconductive film having high reflection efficiency. The transparentconductive film is formed of a material having a comparatively high workfunction value, such as indium-tin-oxide (ITO) or indium-zinc-oxide(IZO), and the opaque conductive film is formed to have a single layerstructure or a multilayer structure including Al, Ag, Cu, Pb, Mo, Ti oran alloy thereof. For example, the upper conductive film 131 b may beformed to have a structure in which a transparent conductive film, anopaque conductive film and a transparent conductive film aresequentially stacked, or a structure in which a transparent conductivefilm and an opaque conductive film are sequentially stacked.

Thereafter, a photosensitive film is stacked on the upper conductivefilm 131 b and is then patterned through a photolithography processusing an eighth mask, such as a multi-tone mask, thus forming amulti-step photosensitive film 149. The multi-step photosensitive film149 is formed to have a first thickness d1 in a region where the padcover electrode 156 will be formed, is formed to have a second thicknessd2 greater than the first thickness d1 in a region where the anode 132and the auxiliary connection electrode 168 will be formed, and is formedto have a third thickness d3 greater than the second thickness d2 in aregion where the bank 138 will be formed. The multi-step photosensitivefilm 149 is not formed in regions between anodes 132, between auxiliaryconnection electrodes 138, between pad cover electrodes 156, and betweenthe anode 132 and the auxiliary connection electrode 138.

By etching the upper conductive film 131 b and the lower conductive film131 a through an etching process using the multi-step photosensitivefilm 149 as a mask, the anode 132, the auxiliary connection electrode168 and the pad cover electrode 156 are formed to have a multilayerstructure including the upper conductive film 131 b and the lowerconductive film 131 a, as exemplarily shown in FIG. 6B. Thereafter, themulti-step photosensitive film 149 is primarily asked so that theoverall thickness of the photosensitive film 149 is reduced and thus theregion of the photosensitive film 149 having the first thickness d1 isremoved, as exemplarily shown in FIG. 6C, thus exposing the upperconductive film 131 b of the pad cover electrode 156. Thereafter, theupper conductive film 131 b is removed through an etching process usingthe primarily ashed multi-step photosensitive film 149 as a mask and,thus, the pad cover electrode 156 includes the lower conductive film 131a alone and the lower conductive film 131 a of each of the anode 132 andthe auxiliary connection electrode 168 and the photosensitive film 149protrude more than the side surface of the upper conductive film 131 bof each of the anode 132 and the auxiliary connection electrode 168.

Thereafter, the multi-step photosensitive film 149 is secondarily ashedand, thus, the overall thickness of the photosensitive film 149 isreduced, as exemplarily shown in FIG. 6D. Therefore, the photosensitivefilm 149 is removed from the upper surfaces of the anode 132 and theauxiliary connection electrode 168 so that the anode 132 and theauxiliary connection electrode 168 are exposed, and the remainingphotosensitive film 149 serves as the bank 138.

With reference to FIG. 51, partitions 146, an organic light emittingstack 134 and a cathode 136 are sequentially formed on the substrate 101provided with the anode 132, the auxiliary connection electrode 168, andthe pad cover electrode 156 and the bank 138.

In more detail, a photosensitive film for partitions is applied to theentire surface of the substrate 101 provided with the bank 138 and isthen patterned through a photolithography process using a ninth mask,thus forming the partitions 146. Thereafter, the organic light emittingstack 134 and the cathode are sequentially formed in the active areaexcept for the pad area through a deposition process using a shadowmask.

As such, in the present disclosure, formation of the anode 132, theauxiliary connection electrode 168, the pad cover electrode 156 and thebank 138 and exposure of the pad cover electrode 156 are carried outthrough one mask process. Further, in the present disclosure, when theupper and lower conductive films 131 a and 131 b forming the anode 132are etched, the pad cover electrode 156 is protected by thephotosensitive film 149 used in formation of the pad cover electrode 156and, thus, damage to the pad cover electrode 156 by an etching solutionor etching gas of the anode 132 may be prevented without a separate padprotective film. Therefore, the method for manufacturing an organiclight emitting display device in accordance with the present disclosuremay decrease the number of times that the mask process is performed byat least three times, as compared to a conventional method, and may thussimplify a structure and a manufacturing process of the organic lightemitting display device and improve productivity of the organic lightemitting display device.

If the organic light emitting display device in accordance with thepresent disclosure has a front view type light emitting structure, theorganic light emitting display device further includes a color filterarray including a black matrix and color filters on a second substrate.In this case, white light emitted from the light emitting element 130exits toward the front surface of the second substrate through the colorfilters, thus displaying an image.

As apparent from the above description, in an organic light emittingdisplay in accordance with the present disclosure, formation of ananode, an auxiliary connection electrode, a pad cover electrode and abank and exposure of the pad cover electrode are carried out through onemask process. Further, when upper and lower conductive films forming theanode are etched, the pad cover electrode is protected by aphotosensitive film used in formation of the pad cover electrode and,thus, damage to the pad cover electrode by an etching solution oretching gas of the anode may be prevented without a separate padprotective film. Therefore, the organic light emitting display device inaccordance with the present disclosure may decrease the number of timesthat the mask process is performed by at least three times, as comparedto a conventional organic light emitting display device, and may thushave a simplified structure and manufacturing process and improveproductivity.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the disclosure. Thus, itis intended that the present disclosure cover the modifications andvariations of this disclosure provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method of manufacturing an organic lightemitting display device comprising: forming thin film transistorsdisposed on a substrate; forming an anode connected to each of the thinfilm transistors and forming a bank disposed along an edge of an anode,simultaneously; and forming a partition disposed to cover a side surfaceof the anode.
 2. The method according to claim 1, further comprising:forming an auxiliary connection electrode connected to a cathodedisposed opposite the anode, simultaneously with formation of the anode;and disposing the bank along the edge of each of the anode and theauxiliary connection electrode.
 3. The method according to claim 2,wherein, in formation of the partition, the partition is formed to coverthe side surface of each of the anode and the auxiliary connectionelectrode.
 4. The method according to claim 1, further comprising:forming pad electrodes disposed in a pad area of the substrate, when thethin film transistors are formed; and forming a pad cover electrodeconnected to a corresponding one of the pad electrodes, when the anodeis formed.
 5. The method according to claim 4, wherein formation of theanode, the auxiliary connection electrode, the pad cover electrode andthe bank includes: sequentially forming a lower conductive film and anupper conductive film on the substrate provided with the thin filmtransistors and the pad electrodes; forming a photosensitive film havinga multi-step structure on the upper conductive film; forming the anode,the auxiliary connection electrode and the pad cover electrode byetching the lower conductive film and the upper conductive film usingthe photosensitive film as a mask; primarily reducing a thickness of thephotosensitive film; removing the upper conductive film of the pad coverelectrode using the photosensitive film having the primarily reducedthickness as a mask; and forming the bank by secondarily reducing athickness of the photosensitive film.